SQL Tune Report–sqltrpt.sql

ORACLE 10g提供了一个脚本sqltrpt.sql用来查询最耗费资源的SQL语句，其输出的结果分为两部分：

15 Most expensive SQL in the cursor cache

15 Most expensive SQL in the workload repository

另外可以根据输入的SQL_ID，生成对应执行计划和调优建议，是一个不错的调优优化脚本。其实是sqltrpt是SQL Tune Report的缩写。这个脚本位于$ORACLE_HOME/rdbms/admin/sqltrpt.sql。 具体脚本如下所示

Rem

Rem $Header: sqltrpt.sql 11-apr-2005.11:01:39 pbelknap Exp $

Rem

Rem sqltrpt.sql

Rem

Rem Copyright (c) 2004, 2005, Oracle. All rights reserved.  

Rem

Rem    NAME

Rem      sqltrpt.sql - SQL Tune RePorT

Rem

Rem    DESCRIPTION

Rem      Script that gets a single statement as input from the user (via SQLID),

Rem      tunes that statement, and then displays the text report.

Rem

Rem      To tune multiple statements, create a sql tuning set and create a

Rem      tuning task with it as input (see dbmssqlt.sql).

Rem

Rem    NOTES

Rem      <other useful comments, qualifications, etc.>

Rem

Rem    MODIFIED   (MM/DD/YY)

Rem    pbelknap    04/11/05 - remove linesize 

Rem    kyagoub     07/05/04 - kyagoub_proj_13448-2

Rem    pbelknap    06/29/04 - feedback from rae burns 

Rem    pbelknap    06/17/04 - Created

Rem

SET NUMWIDTH 10

SET TAB OFF

set long 1000000;

set longchunksize 1000;

set feedback off;

set veri off;

-- Get the sql statement to tune

prompt

prompt 15 Most expensive SQL in the cursor cache

prompt ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

column elapsed format 99,990.90;

variable newl varchar2(64);

begin

  :newl := '

';

end;

/

select * from (

 select sql_id, elapsed_time / 1000000 as elapsed, SUBSTRB(REPLACE(sql_text,:newl,' '),1,55) as sql_text_fragment

 from   V$SQLSTATS

 order by elapsed_time desc

) where ROWNUM <= 15;

prompt

prompt 15 Most expensive SQL in the workload repository

prompt ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

select * from (

 select stat.sql_id as sql_id, sum(elapsed_time_delta) / 1000000 as elapsed, 

     (select to_char(substr(replace(st.sql_text,:newl,' '),1,55)) 

     from dba_hist_sqltext st

     where st.dbid = stat.dbid and st.sql_id = stat.sql_id) as sql_text_fragment

 from dba_hist_sqlstat stat, dba_hist_sqltext text

 where stat.sql_id = text.sql_id and

       stat.dbid   = text.dbid

 group by stat.dbid, stat.sql_id

 order by elapsed desc

) where ROWNUM <= 15;

prompt

prompt Specify the Sql id

prompt ~~~~~~~~~~~~~~~~~~

column sqlid new_value sqlid;

set heading off;

select 'Sql Id specified: &&sqlid' from dual;

set heading on;

prompt

prompt Tune the sql

prompt ~~~~~~~~~~~~

variable task_name varchar2(64);

variable err       number;

-- By default, no error

execute :err := 0;

set serveroutput on;

DECLARE

  cnt      NUMBER;

  bid      NUMBER;

  eid      NUMBER;

BEGIN

  -- If it's not in V$SQL we will have to query the workload repository

  select count(*) into cnt from V$SQLSTATS where sql_id = '&&sqlid';

  IF (cnt > 0) THEN

    :task_name := dbms_sqltune.create_tuning_task(sql_id => '&&sqlid');

  ELSE

    select min(snap_id) into bid

    from   dba_hist_sqlstat

    where  sql_id = '&&sqlid';

    select max(snap_id) into eid

    from   dba_hist_sqlstat

    where  sql_id = '&&sqlid';

    :task_name := dbms_sqltune.create_tuning_task(begin_snap => bid,

                                                  end_snap => eid,

                                                  sql_id => '&&sqlid');

  END IF;

  dbms_sqltune.execute_tuning_task(:task_name);

EXCEPTION

  WHEN OTHERS THEN

    :err := 1;

    IF (SQLCODE = -13780) THEN

      dbms_output.put_line ('ERROR: statement is not in the cursor cache ' ||

                            'or the workload repository.');

      dbms_output.put_line('Execute the statement and try again');

    ELSE

      RAISE;

    END IF;   

END;

/

set heading off;

select dbms_sqltune.report_tuning_task(:task_name) from dual where :err <> 1;

select '   ' from dual where :err = 1;

set heading on;

undefine sqlid;

set feedback on;

set veri on;

一般在sqlplus里面执行下面命令@?/rdbms/admin/sqltrpt即可。它生成调优优化建议是通过调用dbms_sqltune包来完成的。使用它很大程度上方便我们对一些SQL的分析和优化。下面我们构造一个调优例子，如下所示，很简单的一个脚本，其中PRDNO的数据类型为VARCHAR(32),在这个字段上建有唯一索引，但是我们故意构造了下面这样会发生隐式转换的SQL，假设这是某个应用程序发出的脚本，下面会看到一个预估的执行计划是走Index Scan,在sqltrtp里面看到的实际执行计划走全表扫描。

SQL> set linesize 1200

SQL> set autotrace on;

SQL> variable prd_no nvarchar2(20);

SQL> exec :prd_no :='01A10133301I';

PL/SQL procedure successfully completed.

SQL> SELECT  COUNT(1) FROM TEST

  2  WHERE PRDNO=:prd_no  

  3    AND JO_STATUS<>'L2'  

  4    AND STATUS<>'X';

  COUNT(1)

----------

         0

Execution Plan

----------------------------------------------------------

Plan hash value: 2198057827

----------------------------------------------------------------------------------------

| Id  | Operation                    | Name    | Rows  | Bytes | Cost (%CPU)| Time     |

----------------------------------------------------------------------------------------

|   0 | SELECT STATEMENT             |         |     1 |    17 |     3   (0)| 00:00:01 |

|   1 |  SORT AGGREGATE              |         |     1 |    17 |            |          |

|*  2 |   TABLE ACCESS BY INDEX ROWID| TEST    |     1 |    17 |     3   (0)| 00:00:01 |

|*  3 |    INDEX UNIQUE SCAN         | PK_TEST |     1 |       |     2   (0)| 00:00:01 |

----------------------------------------------------------------------------------------

Predicate Information (identified by operation id):

---------------------------------------------------

   2 - filter("JO_STATUS"<>'L2' AND "STATUS"<>'X')

   3 - access("PRDNO"=:PRD_NO)

Statistics

----------------------------------------------------------

          0  recursive calls

          0  db block gets

     112319  consistent gets

     112279  physical reads

          0  redo size

        514  bytes sent via SQL*Net to client

        492  bytes received via SQL*Net from client

          2  SQL*Net roundtrips to/from client

          0  sorts (memory)

          0  sorts (disk)

          1  rows processed

SQL> 

我们先找到该SQL对应的SQL_ID，执行sqltrpt，就会看到对应的分析优化建议，例如它提示语句存在隐式转换，如下截图所示，建议你优化这个问题。